This disclosure relates to subterranean oil and gas wells. More specifically, the disclosure relates to plugging and abandonment of such wells.
Plugging and abandonment of oil and gas production related wellbores can be quite expensive, particularly for subsea wells. Typically, a drilling rig or other type of rig needs to be mobilized and used to place required barriers in the wellbore, as well as to pull tubulars such as velocity tubing strings from the wellbore so that the barriers can be placed and tested.
If production or injection tubing can be permanently left in a wellbore, the time consuming and expensive operation of pulling the tubing out of the wellbore can be avoided. However, the external volume between the tubing and the casing as well as the internal volume of the tubing must be sealed off with a barrier capable of maintaining permanent safety of the wellbore against any possible fluid leakages.
Technologies exist to penetrate a production or injection tubing, where the penetration can be performed by an explosive charge, by a mechanical punch, by a drilling tool and the like. International Application Publication No. WO 2015/175025 entitled, “Multifunction wellbore tubular penetration tool”, describes a tool that can penetrate tubing, remove “window” sections in a tubing as well as cut and remove so called micro tubes (cables, control lines, and similar) that are mounted externally on the tubing string. These openings may be performed at a plurality of different depths in the wellbore. The micro tube removal is performed to eliminate a possible leak path such micro tubes may create, so that a barrier material can be placed between the tubing and casing with minimum risk of leakages.